Combined analysis of Radar T3 and VIMS T20 observations: preliminary results on possible cryovolvanic flows on Titan

Abstract

The Visual and Infrared Mapping Spectrometer (VIMS) aboard Cassini spacecraft allows us to characterize spectral properties of Titan’s surface through the atmosphere in seven narrow windows in the near infrared [1,2]. VIMS acquires images in 64*64 pixels cubes, with a 352 channels spectrum acquired for each pixel. The best resolution obtained so far was 1.4 km/pixel during T4 flyby (31 March 2005). A new observing strategy has been tested during T20 (25 October 2006) in order to observe at closest approach. It consists in acquiring a succession of single lines (using the first scanning mirror), the second dimension of the image being given by the evolution of the groundtrack of the satellite (instead of using the second scanning mirror). This new line mode provides a wider surface coverage than the nominal snapshot mode, and a spatial resolution of ~500 m/pixel at closest approach (which could go down to 250 m/pixel if the double resolution mode is used). We focus here on these new T20 VIMS data which crosses previous observations from the RADAR instrument recorded during the T3 flyby. The radar (in SAR mode) is mainly sensitive to surface roughness, dielectric constant variation and topography, and it can also probe the subsurface materials. Both data sets are therefore very complementary.